Isotretinoin and serum thyroid parameters: systematic review and meta-analysis

Isotretinoin is an effective therapy for acne vulgaris, but its impact on thyroid function remains uncertain, with existing studies reporting inconsistent biochemical changes.

To assess the effects of oral isotretinoin on serum thyroid function parameters and thyroid antibody levels in patients with acne vulgaris.

A systematic review and meta-analysis of observational studies was conducted according to PRISMA guidelines and prospectively registered (INPLASY202560049). PubMed, Scopus, Embase, and Web of Science were searched from January 1980 to September 2025. Studies reporting serum thyroid parameters before and during isotretinoin therapy were included. Random-effects meta-analyses were performed for parameters reported in more than three studies. Heterogeneity was assessed using the I² statistic, and risk of bias using NIH tools.

Fifteen studies were included. Meta-analysis showed a small statistically significant increase in thyroid-stimulating hormone after isotretinoin treatment (MD = 0.03, 95% CI 0.02‒0.05, p < 0.001), with significant decreases in thyroxine (MD = -0.19, 95% CI -0.24 to -0.15, p < 0.001) and triiodothyronine (MD = -0.62, 95% CI-0.76 ‒ -0.48, p < 0.001). Heterogeneity was substantial for thyroid-stimulating hormone (I² = 85%) and triiodothyronine (I² = 86%), and moderate for thyroxine (I² = 60%). Evidence regarding thyroid antibodies was limited and inconsistent.

Included studies were observational, predominantly single-centre, and heterogeneous in dosing, duration, and laboratory assessments.

Isotretinoin is associated with statistically significant alterations in serum thyroid function parameters, though the clinical significance of these changes remains uncertain.